i made a small project, where you can interface any GPS you like with an arduino. The arduino will create telemetry data to feed your frsky telemetry receivers.

It currently only works with Frsky D-Series RXs, but i'm already working on the SPort implementation to use with X-Series as well.
It works with D-Series and X-Series receivers.

The setup is pretty easy and no additional hardware is needed, as all the magic happens in the arduino. Normally you need to invert the serial logic level for frsky receivers. This is already done in the SoftwareSerial implementation.